In DNS, this entry names the mail server that accepts a domain's incoming email. Once it targets Microsoft 365, Exchange Online receives every new message for the domain, so set up mailboxes before making the switch.
Also called mail exchanger record.
Read more: Microsoft Learn
In the Ultra Transcenders books
Each book explains MX record in context, with comparison tables and the common traps.
Terms in this definition
- DNS
The system that turns names into addresses. In Azure, private endpoints depend on private DNS zones, which are queried through 168.63.129.16.
- Domain
A way of grouping workspaces by area of the business, in support of a data mesh approach. Items take on their workspace's domain, letting you filter the OneLake catalog by it, and certain tenant settings can be passed to domain admins; domains have no effect on access permissions.
- Microsoft 365
Formerly Office 365, Microsoft's software-as-a-service productivity suite. A Microsoft Entra tenant provides its identity, and its data is not governed by Azure RBAC.
- Exchange Online
Microsoft 365's hosted service for mail, calendars and contacts. Defender for Office 365 protects these mailboxes.
- Set
Secret permission in Key Vault for writing secrets; some older material refers to it as Create.
- SWITCH
Checks one expression against several candidate values, returning whichever result pairs with the match (or a fallback otherwise). Writing SWITCH ( TRUE (), ... ) avoids nested IF chains: whichever condition is first true wins.
Related terms
- Custom domain
A DNS name of your own attached to a service. In an Entra tenant it is verified through a TXT or MX record, and every on-premises UPN suffix used to sign in must be one (.local can't be); for App Service it is bound with CNAME or TXT validation.
- Custom domain name
A DNS domain you own, contoso.com for example, added to a Microsoft Entra tenant next to the permanent onmicrosoft.com initial domain. Users can sign in with it once you have proved ownership through a TXT or MX record.